update readme

README.md

@@ -10,6 +10,32 @@ Analysis tool for Nextcloud logs files
 logsmash ./logfile.log
 ```
 
+Once the log file is load a list of matched log statements or exception are shown and a histogram for the selected match
+is show on top.
+
+Selecting a match shows a list of distinct log items and selecting a log item shows a list of all occurrences of the log
+message.
+
+## Log matching
+
+Logsmash tries to match the log item to the place in the source where the message originates from. This is either a call
+to a log method or an exception being thrown.
+
+A log item can sometimes be matched to multiple items that are deemed to be equally likely to be the origin of the log
+item.
+In those cases all matches will be shown.
+
+If a log item cannot be matched to an origin it will added to the "Unmatched lines" at the bottom of the list.
+
+## Supported data
+
+Currently, the program can match against data from the following sources:
+
+- Nextcloud server 29
+- files_accesscontrol 1.19.1
+- files_antivirus 5.5.7
+- deck: 1.13.1
+
 ### Updating baked data
 
 rm -r data/src/data